Flexible hose with thrusters for horizontal well drilling

ABSTRACT

A flexible hose assembly for horizontal well drilling is provided. The flexible hose assembly has a number of spaced thruster couplings along its length to impart drilling force to a nozzle blaster at an end of the flexible hose. The thruster couplings have rearwardly oriented thruster ports which impart a forward drilling force upon exit of high pressure water through the thruster ports. At least one of the thruster ports is an adjustable thruster port having variable opening area, variable discharge angle or both. The opening area and discharge angle can be adjusted or controlled to regulate the amount of thrust imparted to the flexible hose and the nozzle blaster, as well as to clear the bore of debris and prevent its accumulation behind the nozzle blaster. A method of horizontal well drilling using the above-described flexible hose is also provided. The method is particularly useful at shallow depths, such as 50-2000 feet.

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/825,329 filed Apr. 3, 2001, which claims thebenefit of U.S. Provisional Patent Application Serial No. 60/195,076filed Apr. 6, 2000.

FIELD OF THE INVENTION

[0002] The invention relates to horizontal well drilling and moreparticularly to a flexible hose assembly for horizontal well drilling.

BACKGROUND OF THE INVENTION

[0003] In the process of drilling for hydrocarbons such as oil andnatural gas, vertical or substantially vertical wells have been usedmost often in the past. Those wells will produce for a given amount oftime, then begin to dry up. At that point, it is advantageous to drillout horizontally or laterally at an angle from the vertical well inorder to try and increase production of, for example, crude oil.

[0004] There have been several attempts to find an economically viableand reliable system for drilling into the untapped pay zones adjacent anexisting vertical well. Horizontal drilling has been proposed as analternative and has been described in U.S. Pat. Nos. 5,853,056,5,413,184, 5,934,390, 5,553,680, 5,165,491, 5,458,209, 5,210,533,5,194,859, 5,439,066, 5,148,877, 5,987,385, 5,899,958, 5,892,460,5,528,566, 4,947,944, 4,646,831, 4,786,874, 5,410,303, 5,318,121,4,007,797, 5,687,806, 4,640,362, 5,394,951, 1,904,819, 2,521,976 and Re.35,386, the contents of all of which are incorporated herein byreference.

[0005] U.S. Pat. No. 5,413,184 describes a method of horizontal drillingthat utilizes a flexible hose and a high pressure nozzle blaster to boreinto the earth's strata at significant depths, such as 4000 feet. Thenozzle blaster uses high pressure water to clear a path through thestrata. The nozzle blaster is advanced through the strata by applyingweight to the hose, i.e., slacking off the tension in the verticalportion of the hose. Essentially, the weight of the 4000 feet of hoseabove the nozzle blaster is used to apply drilling force to the nozzleblaster, thus forcing it along the horizontal path. While this method iseffective at significant depths due to the large amount of weightavailable, it is less effective at shallower depths. At shallow depths,there simply is not enough weight available to supply sufficient forceto advance the nozzle blaster through the strata.

[0006] In addition, drilling substantial lateral or horizontal distancesfrom the vertical well can be very difficult or time consuming orotherwise inhibited due to the accumulation of the loose cuttings fromdrilling in the lateral bore hole.

[0007] Thus, there is a need for an apparatus that will effectivelyadvance a drilling tool such as a nozzle blaster horizontally orlaterally at an angle relative to an existing vertical or substantiallyvertical well, through the earth's strata for horizontal or lateraldrilling at shallow depths. Preferably, such an improved apparatus willalso effectively reduce or prevent the accumulation of cuttings within alateral bore.

SUMMARY OF THE INVENTION

[0008] A flexible hose assembly for horizontal well drilling isprovided. The assembly includes a flexible hose. The flexible hoseassembly has a proximal end and a distal end, wherein the proximal endis located rearward of the distal end. The flexible hose has a pluralityof thruster ports disposed therein with at least one of the thrusterports being disposed rearward of the distal end of the flexible hoseassembly. Each of the thruster ports is adapted to direct a jet ofpressurized fluid in a direction such that a centerline drawn throughthe jet forms an acute discharge angle with the longitudinal axis of theflexible hose rearward from the location of the thruster port. At leastone of the thruster ports is an adjustable thruster port.

[0009] A method of horizontal well drilling is also provided whichincludes the following steps: a) providing a flexible hose assemblyincluding a flexible hose that has a proximal end and a distal end,wherein the proximal end is located rearward of the distal end, theflexible hose having a plurality of thruster ports disposed therein withat least one of the thruster ports being disposed rearward of the distalend of the flexible hose, each of the thruster ports being adapted todirect a jet of pressurized fluid in a direction such that a centerlinedrawn through the jet forms an acute discharge angle with thelongitudinal axis of the flexible hose rearward from the location of thethruster port, at least one of the thruster ports being an adjustablethruster port; b) lowering the flexible hose assembly to a desired depthin a vertical well, and redirecting the flexible hose assembly along adirection at an angle to the longitudinal axis of the vertical well; c)forcing at least 2,000 psi fluid through the flexible hose and thethruster ports in the flexible hose; and d) drilling a horizontal boreinto the earth's strata adjacent the vertical well.

[0010] A flexible hose assembly for horizontal well drilling is alsoprovided. The assembly includes a flexible hose. The flexible hoseassembly has a proximal end and a distal end, wherein the proximal endis located rearward of the distal end. The flexible hose has a pluralityof thruster ports disposed therein with at least one of the thrusterports being disposed rearward of the distal end of the flexible hoseassembly. Each of the thruster ports is adapted to direct a jet ofpressurized fluid in a direction such that a centerline drawn throughthe jet forms an acute discharge angle with the longitudinal axis of theflexible hose rearward from the location of the thruster port. Each ofthe thruster ports has an opening with a cross-sectional area selectedfrom the group consisting of closed polygons, closed curvilinear shapes,and shapes having at least one linear edge.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a side view of a thruster coupling according to a firstpreferred embodiment of the invention.

[0012]FIG. 2 is a cross-sectional view of the thruster coupling takenalong line 2-2 in FIG. 1.

[0013]FIG. 3 is a longitudinal cross-sectional view of the thrustercoupling taken along line 3-3 in FIG. 2.

[0014]FIG. 4 is a perspective view of a flexible hose having thrustercouplings according to the present invention.

[0015]FIG. 5A is a perspective view of a nozzle blaster for use with thepresent invention.

[0016]FIG. 5B is an alternate perspective view of a nozzle blaster foruse with the present invention.

[0017]FIG. 6 is a perspective view of a flexible hose having thrusterports provided directly in the sidewall according to an embodiment ofthe invention.

[0018]FIG. 7 is a side view of a thruster coupling having adjustablethruster ports according to a second preferred embodiment of theinvention.

[0019]FIG. 8 is a cross-sectional view of the thruster coupling takenalong line 8-8 in FIG. 7.

[0020]FIG. 9 is a close-up view of an adjustable thruster port indicatedat broken circle 9 in FIG. 7.

[0021]FIG. 10 is an alternative preferred embodiment of a thrustercoupling having adjustable thruster ports.

[0022]FIG. 11 is a further alternative preferred embodiment of athruster coupling having adjustable thruster ports.

[0023]FIG. 12 is a perspective view of a flexible hose having thrustercouplings according to the embodiment illustrated in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0024] In the description that follows, when a preferred range such as 5to 25 (or 5-25) is given, this means preferably at least 5, andseparately and independently, preferably not more than 25. As usedherein, the following terms having the following meanings: “gal/min”means gallons per minute and “psi” means pounds per square inch.

[0025] As used herein, the term vertical well refers to a well bore inthe earth having an opening at the earth's surface. A vertical well canbe substantially vertical relative to the earth's surface, or it can bedrilled at an angle, e.g. an acute angle, relative to the earth'ssurface instead of straight down. Also as used herein, when a horizontalwell bore or a horizontal well or direction is mentioned, the word“horizontal” indicates a well bore or direction that is at an anglerelative to the vertical well from which the horizontal bore is drilledor depends. For example, as used herein when a horizontal bore isdrilled from a vertical well bore, it is not necessary or required thateither the vertical well bore be truly vertical, or that the horizontalbore drilled therefrom be truly horizontal. All that is required is thatthe vertical well bore have an opening at the earth's surface and thatthe horizontal bore be drilled out from the vertical well at an anglerelative to the vertical well. Commonly, the vertical well is truly orsubstantially vertical, and the horizontal bore drilled therefrom istruly or substantially horizontal; however this is not required ornecessary in the present invention.

[0026] The invention can be used with respect to oil wells, natural gaswells, water wells, solution mining wells, and other wells. Theinvention includes a flexible hose assembly comprising a flexible hosewith thrusters and a nozzle blaster for horizontal well drilling. Thehose assembly is fed down into the bore of an existing vertical well toa specified depth, at which point it is redirected along a horizontaldirection that can be substantially perpendicular to the vertical well.Preferably, the hose assembly is fed into the well by a coil tubinginjector as known in the art. Redirection of the hose assembly ispreferably accomplished via an elbow or shoe in upset tubing as is knownin the art, less preferably via some other known means.

[0027] The hose assembly includes a flexible hose having a proximal endand a distal end, such that proximal end is located rearward of thedistal end. Preferably, the flexible hose is supplied with a pluralityof thruster couplings disposed along the length of the hose. Eachcoupling contains one or more thrusters or thruster ports, each thrusterport comprising a hole or opening through the coupling wall to allow thepassage of water or other pressurized fluid or liquid therethrough. Inone preferred embodiment, the thruster ports are oriented in asubstantially rearward direction about the circumference of the thrustercoupling such that high pressure water or other fluid exits the holes ata substantially rearward angle and enters the horizontal bore in adirection effective to impinge upon the walls of the bore, thusthrusting the hose (and thereby the nozzle blaster) forward through thebore.

[0028] In a further preferred embodiment, the thruster ports areadjustable, meaning that they have variable opening area or diameter,variable discharge angle or both. In this embodiment, the openingdiameter or the angle of discharge of the adjustable thrusters can bevaried to deliver a variable degree of thrust to the hose assembly (andnozzle blaster) depending on how much force is required or desired toeffectively drill through the strata ahead of the nozzle blaster (e.g.sandstone requires comparatively less thrust or drilling force relativeto granite or igneous rock). In addition, varying the angle of dischargecan aid in steering the flexible hose assembly as it drills a horizontalbore, and in clearing the horizontal bore of drill cuttings and otherdebris.

[0029] With reference to FIG. 4, there is shown generally a flexiblehose assembly 10 according to the invention, which preferably comprisesa nozzle blaster 24 and a flexible hose 11. Flexible hose 11 has andcomprises a plurality of flexible hose sections 22, a pair of pressurefittings 23 attached to the ends of each hose section 22, and aplurality of thruster couplings 12, each of which joins a pair ofadjacent pressure fittings 23. Hose assembly 10 comprises a nozzleblaster 24 at its distal end and is connected to a source (not shown) ofhigh pressure fluid, preferably an aqueous liquid, preferably water,less preferably some other liquid, at its proximal end. Couplings 12 arespaced at least, or not more than, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90or 100 feet apart from each other in hose 11. The total hose length ispreferably at least or not more than 100 or 200 or 400 or 600 or 700 or800 or 900 or 1000 or 1200 or 1400 or 1600 or 1800 or 2000 feet. Hosesections 22 are preferably flexible hydraulic hose known in the art,comprising a steel braided rubber-Teflon (polytetrafluoroethylene) mesh,preferably rated to withstand at least 5,000, preferably at least10,000, preferably at least 15,000, psi water pressure. High pressurewater is preferably supplied at at least 2,000, 5,000, 10,000, 15,000,or 18,000 psi, or at 5,000 to 10,000 to 15,000 psi. When used to drillhorizontally from a vertical well, the hose extends about or at least ornot more than 7, 10, 50, 100, 200, 250, 300, 350, 400, 500, 1000, or2000 feet horizontally from the original vertical well. In oneembodiment the hose extends about 440 feet horizontally from theoriginal vertical well.

[0030] As illustrated in FIG. 1, in a first preferred embodimentthruster coupling 12 comprises a coupling or fitting, preferably madefrom metal, preferably steel, most preferably stainless steel, lesspreferably aluminum. Less preferably, coupling 12 is a fitting made fromplastic, thermoset, or polymeric material, able to withstand 5,000 to10,000 to 15,000 psi of water pressure. Still less preferably, coupling12 is a fitting made from ceramic material. It is important to note thatwhen a drilling fluid other than water is used, the material ofconstruction of the couplings 12 must be selected for compatibility withthe drilling fluid and yet still withstand the desired fluid pressure.Coupling 12 has two threaded end sections 16 and a middle section 14.Preferably, end sections 16 and middle section 14 are formed integrallyas a single solid part or fitting. Threaded sections 16 arefemale-threaded to receive male-threaded pressure fittings 23 which areattached to, preferably crimped within the ends of, hose sections 22(FIG. 4). Alternatively, the fittings 23 can be attached to the ends ofthe hose sections 22 via any conventional or suitable means capable ofwithstanding the fluid pressure. In the illustrated embodiment, eachfitting 23 has a threaded portion and a crimping portion which can be aunitary or integral piece, or a plurality of pieces joined together asknown in the art. Alternatively, the threaded connections may bereversed; i.e. with male-threaded end sections 16 adapted to mate withfemale-threaded pressure fittings attached to hose sections 22. Lesspreferably, end sections 16 are adapted to mate with pressure fittingsattached to the end of hose sections 22 by any known connecting meanscapable of providing a substantially water-tight connection at highpressure, e.g. 5,000-15,000 psi. Middle section 14 contains a pluralityof holes or thruster ports 18 which pass through the thickness of wall15 of coupling 12 to permit water to jet out. Though the thruster ports18 are shown having an opening with a circular cross-section, thethruster port openings can be provided having any desired cross section;e.g. polygonal, curvilinear or any other shape having at least onelinear edge, such as a semi-circle. Coupling 12 preferably is shortenough to allow hose 11 to traverse any bends or elbows in the upsettubing and any shoes or adapters used therewith. Therefore, coupling 12is formed as short as possible, preferably having a length of less thanabout 3, 2, or 1.5 inches, more preferably about 1 inch or less than 1inch. Hose 11 (and therefore couplings 12 and hose sections 22)preferably has an outer diameter of about 0.25 to about 1.25 inches,more preferably about 0.375 to about 0.5 inches, and an inner diameterpreferably of about 0.125 inches. Couplings 12 have a wall thickness ofpreferably about 0.025-0.25, more preferably about 0.04-0.1, inches.

[0031] Optionally, hose 11 is provided with couplings 12 formedintegrally therewith, or with thruster ports 18 disposed directly in thesidewall of a contiguous, unitary, non-sectioned hose at spacedintervals along its length (see FIG. 6). A hose so comprised obviatesthe need of threaded connections or other connecting means as describedabove.

[0032] In the embodiments shown in FIGS. 1 and 7, thruster ports 18 havehole axes 20 which form a discharge angle β with the longitudinal axisof the coupling 12. The discharge angle β is preferably 5° to 95°, morepreferably 10° to 90°, more preferably 10° to 80°, more preferably 15°to 70°, more preferably 20° to 60°, more preferably 25° to 55°, morepreferably 30° to 50°, more preferably 40° to 50°, more preferably 40°to 45°, more preferably about 45°. The thruster ports 18 are alsooriented such that a water jet passing through them exits the coupling12 in a substantially rearward direction; i.e. in a direction such thata centerline drawn through the exiting water jet forms an acute angle(discharge angle β) with the longitudinal axis of the flexible hoserearward from the location of the thruster port, toward the proximal endof the hose assembly. In this manner, high-pressure water jets 30emerging from thruster ports 18 impart drilling force or thrust to thenozzle blaster, thus forcing the nozzle blaster forward into the earthstrata (see FIG. 4). As illustrated in FIG. 2, a plurality of thrusterports 18 are disposed in wall 15 around the circumference of coupling12. There are 2 to 6 or 8 ports, more preferably 3 to 5 ports, morepreferably 3 to 4 ports. Thruster ports 18 are spaced uniformly aboutthe circumference of coupling 12, thus forming an angle α between them.Angle α will depend on the number of thruster ports 18, and thuspreferably will be from 45° or 60° to 180°, more preferably 72° to 120°,more preferably 90° to 120°. Thruster ports 18 are preferably about0.010 to 0.017 inches, more preferably 0.012 to 0.016 inches, morepreferably 0.014 to 0.015 inches in diameter.

[0033] As best seen in FIGS. 1 and 2, thruster ports 18 are formed inthe wall 15 of coupling 12, extending in a substantially rearwarddirection toward the proximal end of the hose assembly 10, connectinginner opening 17 at the inner surface of wall 15 with outer opening 19at the outer surface of wall 15. The number of couplings 12, as well asthe number and size of thruster ports 18 depends on the desired waterpressure and water flow rate. If a water source of only moderatedelivery pressure is available, e.g. 5,000-7,000 psi, then relativelyfewer couplings 12 and thruster ports 18, as well as possibly smallerdiameter thruster ports 18 should be used. However, if higher pressurewater is supplied, e.g. 10,000-15,000 psi, then more couplings 12 andthruster ports 18 can be utilized. The number of couplings 12 andthruster ports 18, the diameter of thruster ports 18, and the initialwater pressure and flow rate are all adjusted to achieve water flowrates through nozzle blaster 24 of 1-10, more preferably 1.5-8, morepreferably 2-6, more preferably 2.2-3.5, more preferably 2.5-3, gal/min.

[0034] In the first preferred embodiment illustrated in FIG. 1, thethruster ports 18 are provided as unobstructed openings or holes throughthe side wall of the thruster coupling 12. The ports 18 are provided ordrilled at an angle so that the exiting pressurized fluid jets in arearward direction as explained above.

[0035] In the second preferred embodiment illustrated in FIG. 7, thethruster couplings 12 and thruster ports 18 are similarly provided asdescribed above shown in FIG. 1, except that the thruster port or ports18 include a shutter 31. The shutter 31 is preferably an iris as shownin FIG. 7, and shown close-up in FIG. 9. The shutter 31 is actuated by aservo controller 32 (pictured schematically in the figures) which iscontrolled by an operator at the surface via wireline, radio signal orany other suitable or conventional means. The servo controller 32 ispreferably provided in the sidewall of the coupling 12 as shown in FIG.8, or is mounted on the inner wall surface of the coupling 12. The servocontroller 32 has a small motor to control or actuate the shutter 31 tothereby regulate the diameter or area of the opening 34 for the thrusterport 18. A fully open shutter 31 results in the maximum possible thrustfrom the associated thruster port 18 because the maximum area isavailable for the expulsion of high pressure fluid. An operator cannarrow the opening 34 by closing the shutter 31 to regulate the amountof thrust imparted to the hose assembly by the associated thruster port18. The smaller diameter the opening 34, the less thrust provided by thethruster port 18. Although an iris is shown, it will be understood thatother mechanisms can be provided for the shutter 31 which areconventional or which would be recognized by a person of ordinary skillin the art; e.g. sliding shutter, flap, etc. The servo controller 32 ispreferably a conventional servo controller having a servo motor that iscontrolled in a conventional manner. Servo controllers are generallyknown or conventional in the art.

[0036] In addition to providing thrust to the hose (and nozzle blaster24), thruster ports 18 equipped with shutters 31 can be used to guide orsteer the hose assembly 10 as it drills a horizontal bore. It will beunderstood by a person of ordinary skill in the art that during use, thehose assembly 10 is very rigid, i.e. it is biased in a straight orlinear configuration due to the internal fluid pressure (e.g. 5,000 or10,000 or 15,000 psi). This is because the internal fluid pressure seeksto expand the hose assembly 10 from within, thereby forcing the assemblyto remain stiff and straight without bending. By regulating the relativethrust provided by different thruster ports 18 at spaced circumferentiallocations about the hose assembly at a particular axial position alongits length, the assembly 10 can be steered at that axial location.

[0037] For example, referring to FIG. 8, if thruster port 18 a providesgreater thrust than either of ports 18 b or 18 c, then the hose assembly10 will be driven in a lateral direction (relative to the hose'slongitudinal axis) substantially opposite the position of the thrusterport 18 a as a result of the excess thrust (i.e. direction indicated byarrow B in FIG. 8). The lateral thrust is countered by and must bebalanced against the assembly's 10 straight and rigid bias (describedabove) to provide the desired lateral positioning or steering effect.The assembly's straight and rigid bias makes control of the assembly 10via the thrusters easier to achieve because the assembly is constantlytrying to right or straighten itself. Therefore, the thrusters' portopenings 34 can be finely regulated to control the amount of thrustacting against the straightening bias to provide very precise lateralpositioning and steering capability for the hose assembly 10.

[0038] Likewise, a corresponding lateral thrust can be imparted byeither of thruster ports 18 b and/or 18 c in the appropriate direction.It will be understood that the relative thrust of all the thrusterslocated at the same axial position along the length of the hose assembly10 (i.e. all the thrusters in a single thruster coupling 12) can besimultaneously regulated in concert to guide the lateral position of thehose assembly 10 at that location. By similarly coordinating therelative thrust of all the groups of thruster ports 18 disposed atdiscrete axial positions along the length of the hose assembly 10, anoperator can guide or steer the assembly 10 as it drills horizontallyfrom the vertical well to thereby provide a specific desiredconfiguration for the hose assembly 10 along its entire length as itdrills. This way, a horizontal bore having a desired nonlinear shape oroverall configuration can be drilled; the horizontal bore need not bestraight. Alternatively, if a straight or linear horizontal bore isdesired, the hose assembly 10 (particularly at or near its distal endwhere the nozzle blaster 24 is located) can be steered to ensure astraight path despite the presence of obstructions or other forces thatcould divert the blaster's 24 path.

[0039] It will be understood that when complex shape or drilling pathwayconfigurations are desired, it would be very difficult for a humanoperator to properly control and regulate the relative thrust for all ofthe thruster ports 18 along the hose assembly's length. Therefore, it isdesirable and preferred to have the adjustable thruster ports 18controlled by a computer 40 that has been programmed with the desireddrilling configuration. Means and methods for programming a computer tocontrol a plurality of servo controllers (for regulating shutters 31)are conventional, and are well understood by persons of ordinary skillin the art.

[0040] Preferably, the flexible hose 11 is provided with a plurality ofposition indicating sensors 35 along its length. Position indicatingsensors 35 are shown schematically in FIG. 4 attached to the thrustercouplings 12 and nozzle blaster 24. Alternatively, the positionindicating sensors 35 can be provided in the coupling walls, or in thehose wall along its length. The position indicating sensors 35 can emita radio signal or can be monitored by wireline from the surface todetermine the location and configuration of the flexible hose. Theadjustable thruster ports 18 can be controlled as described above basedon position and configuration information received from these positionindicating sensors 35. Preferably, the computer receives informationfrom the position indicating sensors 35 and regulates the adjustablethrusters based on that information to achieve the desired steering andposition control of the hose assembly 10 as it drills a horizontal bore.

[0041]FIG. 10 shows an alternative preferred embodiment of theadjustable thruster ports 18. In this embodiment, the adjustablethruster ports 18 comprise flap shutters 31 a adjacent to, and adaptedto seal off, the outer openings 19 of the ports 18. In this embodiment,the flap shutters 31 a are servo controlled similarly as describedabove, and can be opened or closed to variable degrees as desired toprovide a desired amount of thrust. One advantage of this embodiment isthat in addition to regulating the flowrate of the jets 30, the flapshutters 31 a also can be used to regulate the discharge angle β. Thisembodiment is less preferred because the flap shutters 31 a are liableto catch on the horizontal bore wall or on some obstruction therein.Further, the flap shutters can inhibit the passage of rearwardlytraveling cuttings to exit the horizontal bore as described below.

[0042]FIG. 11 shows yet another alternative preferred embodiment of theinvention, where the thruster ports 18 are provided in servo-controlledpivot arms 38. In this embodiment, the discharge angle β between thecenterline drawn through the exiting water jet 30 and the longitudinalaxis of the flexible hose can be regulated. The smaller angle β, thelarger axial thrust force vector for a given fluid pressure anddischarge rate; conversely, the larger angle β, the smaller axial thrustforce vector for the same fluid pressure and discharge rate. Thus, thedegree of forward thrust for the hose assembly 10 can be controlled fora given fluid pressure and discharge rate by regulating the dischargeangle of the water jets 30. This is achieved by controlling the pivotarms 38 to provide the desired discharge angle β. Preferably, the pivotarms 38 are adjustable to provide a discharge angle in the range of 10°to 90°, 10° to 80°, 15° to 70°, 20° to 60°, 25° to 50°, 30° to 50°, or40° to 50° in a rearward direction toward the proximal end of the hoseassembly 10.

[0043] In addition to providing thrust, the thruster ports 18 alsoprovide another important function. Thruster ports 18 keep the boreclear behind nozzle blaster 24 as the rearwardly jetting high pressurefluid (water) washes the drill cuttings out of the horizontal bore sothat the cuttings do not accumulate in the horizontal bore. The highpressure water or aqueous liquid forced through the thruster ports 18also cleans and reams the bore by clearing away any sand and dirt thathas gathered behind the advancing nozzle blaster 24, as well assmoothing the wall of the freshly drilled bore.

[0044] This is an important feature because, left to accumulate, thecuttings and other debris can present a significant obstacle tohorizontal drilling, effectively sealing of already-drilled portions ofthe horizontal bore around the advancing hose assembly 10. This can makeremoval of the hose assembly 10 difficult once drilling is completed. Ina worst case, the remaining debris can cause the horizontal bore toreseal once the hose assembly 10 has been withdrawn. By forcing thesecuttings rearward to exit the lateral bore, the rearwardly directedwater jets 30 ensure the horizontal bore remains substantially open andclear after drilling is completed and the hose assembly 10 is removed.By providing the thruster ports 18 along substantially the entire lengthof the hose assembly 10, drill cuttings can be driven out of thehorizontal bore from great distances into the horizontal bore,preferably at least 50, 100, 200, 250, 300, 350, 400, 500, 1000, ormore, feet.

[0045] Nozzle blaster 24 is of any type known in the art, for example,the type shown in FIGS. 5A-5B. Nozzle blaster 24 comprises a pluralityof holes 50 disposed about a front portion 46 a which preferably has asubstantially domed shape. Holes 50 are positioned to form angle θ withthe longitudinal axis of nozzle blaster 24. Angle θ is 10°-30°, morepreferably 15°-25°, more preferably about 20°. Nozzle blaster 24 alsocomprises a plurality of holes 46 b, which are oriented in a reverse orrearward direction on a rear portion 60 of nozzle blaster 24, thedirection and diameter of holes 46 b being similar to that of thrusterports 18 disposed around couplings 12. Holes 46 b serve a similarfunction as thruster ports 18 to impart forward drilling force to nozzleblaster 24 and to wash drill cuttings rearward to exit the horizontalbore. Optionally, front portion 46 a is rotatably coupled to rearportion 60, with holes 50 oriented at an angle such that exitinghigh-pressure water imparts rotational momentum to front portion 46 a,thus causing front portion 46 a to rotate while drilling. Rear portion60 is either fixed with respect to hose 11 unable to rotate, or isrotatably coupled to hose 11 thus allowing rear portion 60 to rotateindependently of hose 11 and front portion 46 a. In this embodiment,holes 46 b are oriented at an angle effective to impart rotationalmomentum to rear portion 60 upon exit of high-pressure water, thuscausing rear portion 60 to rotate while drilling. Holes 50 and 46 b canbe oriented such that front and rear portions (46 a and 60 respectively)rotate in the same or opposite directions during drilling.

[0046] Thruster ports 18 and 46 b are oriented in a reverse or rearwarddirection, relative to forward direction A (FIGS. 1 and 4), toward theproximal end of the hose assembly to thrust the nozzle blaster forwardto drill the bore. High pressure water is propelled through thrusterports 18 forming high pressure water jets 30 which impinge on the wallsof the bore at such an angle as to impart drilling force to the nozzleblaster 24. Thus, the present invention has great utility at shallowdepths where the length (and thereby the weight) of flexible hose in thevertical well is generally insufficient to supply adequate drillingforce to the nozzle blaster 24 to propel it forward while drilling. Assuch, the present invention is effectively used to drill horizontalbores at depths of at least, or not more than, 50, 100, 200, 300, 400,500, 600, 700, 800, 900, 1000, or 2000 feet. However, the invented hoseassembly can also be advantageously used to drill horizontal bores atgreater depths, e.g. 5,000, 8,000, 10,000, or 15,000 feet or greater.

[0047] Although the hereinabove described embodiments of the inventionconstitute the preferred embodiments, it should be understood thatmodifications can be made thereto without departing from the scope ofthe invention as set forth in the appended claims.

What is claimed is:
 1. A flexible hose assembly for horizontal welldrilling comprising a flexible hose, said flexible hose assembly havinga proximal end and a distal end, said proximal end being locatedrearward of said distal end, said flexible hose having a plurality ofthruster ports disposed therein with at least one of said thruster portsbeing disposed rearward of said distal end of said flexible hoseassembly, at least one of said thruster ports being adapted to direct ajet of pressurized fluid in a direction such that a centerline drawnthrough said jet forms an acute discharge angle with the longitudinalaxis of said flexible hose rearward from the location of said thrusterport, at least one of said thruster ports being an adjustable thrusterport.
 2. A flexible hose assembly according to claim 1, said flexiblehose further comprising a plurality of flexible hose sections and atleast one thruster coupling, said thruster coupling being joined toadjacent flexible hose sections, said adjustable thruster port beingdisposed in said thruster coupling.
 3. A flexible hose assemblyaccording to claim 2, further comprising a plurality of said thrustercouplings, each thruster coupling having at least one adjustablethruster port.
 4. A flexible hose assembly according to claim 1, saidhose comprising flexible hydraulic hose rated to withstand at least5,000 psi.
 5. A flexible hose assembly according to claim 3, saidthruster couplings being spaced at least 10 feet apart from each otherin said hose.
 6. A flexible hose assembly according to claim 3, each ofsaid thruster couplings comprising two threaded end sections and amiddle section, each of said end sections adapted to mate with apressure fitting attached to a section of said flexible hose.
 7. Aflexible hose assembly according to claim 1, said adjustable thrusterport having a variable opening area, said jet being discharged from saidthruster port through said opening.
 8. A flexible hose assemblyaccording to claim 1, said adjustable thruster port having a variabledischarge angle.
 9. A flexible hose assembly according to claim 7, saidadjustable thruster port comprising a shutter for regulating the area ofsaid opening of said thruster port.
 10. A flexible hose assemblyaccording to claim 9, said shutter being an iris.
 11. A flexible hoseassembly according to claim 9, further comprising a servo controller foractuating said shutter to thereby regulate said opening area of saidadjustable thruster port.
 12. A flexible hose assembly according toclaim 11, said servo controller being controlled via wireline or radiosignal.
 13. A flexible hose assembly according to claim 2, said thrustercoupling comprising 2-8 thruster ports evenly spaced around thecircumference of said thruster coupling.
 14. A flexible hose assemblyaccording to claim 8, said adjustable thruster port comprising aservo-controlled pivot arm, said pivot arm being adjustable to regulatesaid discharge angle.
 15. A flexible hose assembly according to claim14, said pivot arm being adjustable to provide said discharge angle inthe range of 10° to 90° in a rearward direction toward said proximal endof said hose assembly.
 16. A flexible hose assembly according to claim1, said flexible hose being 400-2000 feet in length.
 17. A flexible hoseassembly according to claim 1, further comprising a nozzle blasterjoined to said flexible hose at said distal end of said hose assembly,at least one of said thruster ports being disposed in said flexible hoserearward of the point where said flexible hose joins said nozzleblaster.
 18. A method of horizontal well drilling comprising thefollowing steps: a) providing a flexible hose assembly comprising aflexible hose having a proximal end and a distal end, said proximal endbeing located rearward of said distal end, said flexible hose having aplurality of thruster ports disposed therein with at least one of saidthruster ports being disposed rearward of said distal end of saidflexible hose, at least one of said thruster ports adapted to direct ajet of pressurized fluid in a direction such that a centerline drawnthrough said jet forms an acute discharge angle with the longitudinalaxis of said flexible hose rearward from the location of said thrusterport, at least one of said thruster ports being an adjustable thrusterport; b) lowering said flexible hose assembly to a desired depth in avertical well, and redirecting said flexible hose assembly along adirection at an angle to the longitudinal axis of said vertical well; c)forcing at least 2,000 psi fluid through said flexible hose and saidthruster ports in said flexible hose; and d) drilling a horizontal boreinto the earth's strata adjacent said vertical well.
 19. A methodaccording to claim 18, said adjustable thruster port having a variableopening area, said jet being discharged from said thruster port throughsaid opening.
 20. A method according to claim 18, said adjustablethruster port having a variable discharge angle.
 21. A method accordingto claim 19, said adjustable thruster port comprising a shutter forregulating the area of said opening of said thruster port.
 22. A methodaccording to claim 21, said shutter being an iris.
 23. A methodaccording to claim 21, further comprising a servo controller foractuating said shutter to thereby regulate said opening area of saidadjustable thruster port.
 24. A method according to claim 23, said servocontroller being controlled via wireline or radio signal.
 25. A methodaccording to claim 20, said adjustable thruster port comprising aservo-controlled pivot arm, said pivot arm being adjustable to regulatesaid discharge angle.
 26. A method according to claim 25, said pivot armbeing adjustable to provide said discharge angle in the range of 10° to90° in a rearward direction toward said proximal end of said hoseassembly.
 27. A method according to claim 18, further comprising thestep of drilling a horizontal bore from a vertical well at a depth of50-2000 feet.
 28. A method according to claim 18, further comprising thestep of withdrawing said hose assembly from said horizontal bore, andduring said withdrawing step forcing fluid through said thruster portsto clean and ream said horizontal bore.
 29. A method according to claim18, said flexible hose assembly further comprising a nozzle blasterattached to said flexible hose at said distal end thereof, at least oneof said thruster ports being disposed in said flexible hose rearward ofthe point where said flexible hose joins said nozzle blaster.
 30. Aflexible hose assembly according to claim 1, said fluid being aqueousliquid.
 31. A method according to claim 18, said fluid being aqueousliquid.
 32. A flexible hose assembly according to claim 1, furthercomprising at least one position indicating sensor.
 33. A flexible hoseassembly according to claim 32, comprising a plurality of said positionindicating sensors provided along the length of said flexible hoseassembly.
 34. A flexible hose assembly for horizontal well drillingcomprising a flexible hose, said flexible hose assembly having aproximal end and a distal end, said proximal end being located rearwardof said distal end, said flexible hose having a plurality of thrusterports disposed therein with at least one of said thruster ports beingdisposed rearward of said distal end of said flexible hose assembly, atleast one of said thruster ports being adapted to direct a jet ofpressurized fluid in a direction such that a centerline drawn throughsaid jet forms an acute discharge angle with the longitudinal axis ofsaid flexible hose rearward from the location of said thruster port,each of said thruster ports having an opening with a cross-sectionalarea selected from the group consisting of closed polygons, closedcurvilinear shapes, and shapes having at least one linear edge.